1. Twenty Questions Electricity 2

2. Twenty Questions 12345 678910 1112131415 1617181920

3. 1. Give 1 advantage of using a circuit breaker compared with a fuse. Reset instead of replaced. Easier to see if it’s off.

4. 2. What type of appliance uses the greatest power? One which produces heat.

5. 3. Upon what does the size of an appliances flex depend? It’s power rating.

6. 4. In a house are the mains wires in series or parallel? Why? Parallel. So each appliance can be switched on/off separately. Each appliance will have 230V across it.

7. 5. A heater has a current of 6A flowing through it for 4 minutes, what charge will pass through it. Q = It = 6 x (4 x 60) = 1440 C

8. 6. Draw the electrical field surrounding a negative point charge.

9. 7. State Ohm’s Law R = V ÷ I

10. 8. Draw the symbol for a fuse. Rectangle with the wire passing through it.

11. 9. Give an example each of a d.c. and an a.c. power source. d.c – battery a.c - mains.

12. 10. If a heater uses 1500 J of energy each second, What current will it draw if it is working from the mains voltage? V = 230V P = 1500W as P = E / t I = P ÷ V = 1500 ÷ 230 = 6.5 A

13. 11. Calculate the current in a circuit if 135 charges take 3minutes to travel through the circuit. Q = I t t = 3x60 =180s I = Q/t I = 135/180 I = 0.75A

14. 12. What are the values of the voltage and frequency of the mains supply? 230V 50Hz

15. 13. What is current? The rate of flow of electric charges around a circuit. The charge per second that passes a point.

16. 14. What are the units for charge? Coulombs, C

17. 15. Describe how electrons move in ac and dc. dc electrons move from negative to positive. Ac electrons vibrate backwards and forwards, changing direction

18. 16. What danger is present when using a multiway adapter? If too many appliances are used or ones which require much current are used it may overheat and catch fire.

19. 17. Calculate the number of electrons that pass through a wire carrying a current of 2 A for 5 s. Q electron = 1.6x10 -19 C Q = It = 2 x 5 = 10C No. of electrons =10 ÷ 1.6x10 -19 = 6.25 x 10 19

20. 18. What type of current is shown by the waveform? a.c / alternating current

21. 19. Why must the fuse value be greater than the current used by the appliance? It melts when it’s rating/value has been reached. So in normal use it does not melt but if something goes wrong it melts before anything else does.

22. 20. What fuse should be used in a 2kW kettle, 3A or 13A? Show working. I=P/V I=2000/230 I=8.7A 13A fuse.